Module arranged to bidirectionally pass coupled power signal

ABSTRACT

Aspects of this disclosure relate to a radio frequency module with a radio frequency coupler and a coupler switching circuit. The coupler switching circuit can provide an indication of radio frequency power generated by the radio frequency coupler to a first input/output port. The coupler switching circuit can also pass an indication of radio frequency power received at the first input/output port to a second input/output port, and pass an indication of radio frequency power received at the second input/output port to the first input/output port.

CROSS REFERENCE TO PRIORITY APPLICATION

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 C.F.R. § 1.57.This application claims the benefit of priority of U.S. ProvisionalApplication No. 63/085,835, filed Sep. 30, 2020 and titled “MODULEARRANGED TO BI-DIRECTIONALLY PASS COUPLER SIGNAL,” the disclosure ofwhich is hereby incorporated by reference in its entirety.

BACKGROUND Technical Field

Embodiments of this disclosure relate to radio frequency modules andradio frequency systems.

Description of Related Technology

Radio frequency (RF) communication systems can be used for transmittingand/or receiving signals of a wide range of frequencies. For example, anRF communication system can be used to wirelessly communicate RF signalsin a frequency range from about 30 kHz to about 300 GHz, such as in therange of about 410 megahertz (MHz) to about 7.125 gigahertz (GHz) forFifth Generation (5G) cellular communications in Frequency Range 1(FR1).

Example of RF communication systems can include without limitationmobile phones, tablets, base stations, network access points,customer-premises equipment (CPE), laptops, and wearable electronics.

In certain applications, RF communications systems can generate aplurality of RF signals concurrently for transmission. In such RFcommunications systems, determining power associated with an individualradio frequency signal can be useful.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

The innovations described in the claims each have several aspects, nosingle one of which is solely responsible for its desirable attributes.Without limiting the scope of the claims, some prominent features ofthis disclosure will now be briefly described.

One aspect of this disclosure is a radio frequency system that includesa first radio frequency module having a first port, a second radiofrequency module having a second port, and a third radio frequencymodule. The third radio frequency modules includes a first input/outputport electrically connected to the first port, a second input/outputport electrically connected to the second port, and a coupler switchingcircuit. The coupler switching circuit is configured to pass anindication of radio frequency power received at the first input/outputport to the second input/output port and pass an indication of radiofrequency power received at the second input/output port to the firstinput/output port.

The third radio frequency module can include a radio frequency coupler.The coupler switching circuit can provide an indication of radiofrequency power from the radio frequency coupler to the firstinput/output port. The indication of radio frequency power from theradio frequency coupler can be an indication of forward radio frequencypower. The coupler switching circuit can provide an indication ofreflected radio frequency power from the radio frequency coupler to thefirst input/output port. The coupler switching circuit can provide theindication of radio frequency power from the radio frequency coupler tothe second input/output port.

The radio frequency system can include a feedback receiver having aninput port electrically coupled to a daisy chain that includes thecoupler switching circuit. The daisy chain can include a couplerswitching circuit of the first radio frequency module and a couplerswitching circuit of the second radio frequency module. The radiofrequency system can include a switch coupled between the input port ofthe feedback receiver and the daisy chain. The feedback receiver caninclude a second port electrically coupled to the daisy chain. The daisychain can include a T-connection that combines two traces, in which thedaisy chain is connected to a single input port of the feedbackreceiver. The coupler switching circuit can be configured to pass anindication of radio frequency power having a direct current componentand a radio frequency component. The radio frequency system can alsoinclude a direct current blocking element coupled between the daisychain and the input port of the feedback receiver. The third radiofrequency module and another module in the daisy chain can concurrentlyoutput radio frequency signals. The feedback receiver can receiveindications of radio frequency power associated with each of theconcurrently output radio frequency signals. The radio frequency systemcan pass the indications of radio frequency power in opposite directionsin the daisy chain. The third radio frequency module and another modulein the daisy chain can concurrently output radio frequency signals in acarrier aggregation mode. The third radio frequency module and anothermodule in the daisy chain can concurrently output radio frequencysignals in a dual connectivity mode.

The second module can include a third port and a second couplerswitching circuit. The second coupler switching circuit can pass anindication of radio frequency power received at the second port to thethird port and pass an indication of radio frequency power received atthe third port to the second port.

Another aspect of this disclosure is a method of passing coupled powersignals. The method includes providing a first coupled power signalgenerated by a first radio frequency module to a daisy chain, andproviding a second coupled power signal generated by a second radiofrequency module to the daisy chain such that the first coupled powersignal and the second coupled power signal propagate in oppositedirections in the daisy chain. The method is performed while the firstradio frequency module and the second radio frequency module aretransmitting concurrently.

The method can include receiving the first coupled power signal and thesecond coupled power signal at a feedback receiver. The method caninclude causing at least one adjustment to a transmit path of the firstradio frequency module based on an output signal from the feedbackreceiver.

The method can include passing the first coupled power signal throughcircuitry of a third radio frequency module in the daisy chain.

Another aspect of this disclosure is a wireless communication devicethat includes a radio frequency system and one or more antennas incommunication with the radio frequency system. The radio frequencysystem includes a first radio frequency module having a first port, asecond radio frequency module having a second port, and a third radiofrequency module. The third radio frequency module includes a firstinput/output port electrically connected to the first port, a secondinput/output port electrically connected to the second port, and acoupler switching circuit. The coupler switching circuit is configuredto pass an indication of radio frequency power received at the firstinput/output port to the second input/output port and pass an indicationof radio frequency power received at the second input/output port to thefirst input/output port. The one or more antenna are configured to atransmit radio frequency signal generated by the first radio frequencymodule.

The wireless communication device can be a mobile phone.

Another aspect of this disclosure is a radio frequency that includes afirst input/output port, a second input/output port, a radio frequencycoupler, and a coupler switching circuit. The coupler switching circuitis configured to pass an indication of radio frequency power received atthe first input/output port to the second input/output port, pass anindication of radio frequency power received at the second input/outputport to the first input/output port, and provide an indication of radiofrequency power from the radio coupler to the first input/output port.

The coupler switching circuit can provide the indication of radiofrequency power from the radio frequency coupler to the secondinput/output port.

The indication of radio frequency power can be an indication of forwardradio frequency power. The coupler switching circuit can provide anindication of reflected radio frequency power from the radio frequencycoupler to the first input/output port. The coupler switching circuitcan provide the indication of radio frequency power to the secondinput/output port and provide the indication of reflected radiofrequency power to the second input/output port.

The radio frequency module can include a power amplifier having anoutput electrically coupled to the radio frequency coupler. The radiofrequency module can include one or more circuit elements in a signalpath between the output of the power amplifier and the radio frequencycoupler. The one or more circuit elements can include a switch. The oneor more circuit elements can include a filter.

The radio frequency module can include a second radio frequency coupler.The coupler switching circuit can provide an indication of radiofrequency power from second radio frequency coupler to the firstinput/output port.

The coupler switching circuit can includes a plurality of switchesarranged to pass the indication of radio frequency power received at thefirst input/output port to the second input/output port, pass theindication of radio frequency power received at the second input/outputport to the first input/output port, and provide the indication of radiofrequency power from the radio coupler to the first input/output port.The plurality of switches can include a switch configured to selectivelyelectrically connect a termination impedance to a port of the radiofrequency coupler.

Another aspect of this disclosure is a radio frequency system thatincludes a first radio frequency module including a first port and afirst coupler switching circuit, a second radio frequency moduleincluding a second coupler switching circuit, and a third radiofrequency module. The third radio frequency module includes a firstinput/output port, a second input/output port, a radio frequencycoupler, and a third coupler switching circuit. The third couplerswitching circuit is included in a daisy chain that also includes thefirst and second coupler switching circuits. The third coupler switchingcircuit is configured to pass an indication of radio frequency powerreceived at the first input/output port to the second input/output port,pass an indication of radio frequency power received at the secondinput/output port to the first input/output port, and provide anindication of radio frequency power from the radio coupler to the firstinput/output port.

The third coupler switching circuit can provide the indication of radiofrequency power from the radio frequency coupler to the secondinput/output port.

The indication of radio frequency power can be an indication of forwardradio frequency power. The third coupler switching circuit can providean indication of reflected radio frequency power from the radiofrequency coupler to the first input/output port.

The third radio frequency module can include a second radio frequencycoupler. The third coupler switching circuit can provide an indicationof radio frequency power from second radio frequency coupler to thefirst input/output port.

The first radio frequency module and the second radio frequency modulecan be configured to transmit concurrently. The radio frequency systemcan concurrently pass a first indication of radio frequency power fromthe first radio frequency module and a second indication of radiofrequency power from the second radio frequency module in differentdirections in the daisy chain.

The radio frequency system can include a feedback receiver having aninput port electrically coupled to the daisy chain.

Another aspect of this disclosure is a wireless communication devicethat includes a radio frequency module and an antenna in communicationwith the radio frequency module. The radio frequency module includes afirst input/output port, a second input/output port, a radio frequencycoupler, and a coupler switching circuit. The coupler switching circuitis configured to pass an indication of radio frequency power received atthe first input/output port to the second input/output port, pass anindication of radio frequency power received at the second input/outputport to the first input/output port, and provide an indication of radiofrequency power from the radio coupler to the first input/output port.The antenna is configured to transmit a radio frequency signal generatedby the radio frequency module.

The wireless communication device can include two additional radiofrequency modules each including a respective coupler circuit that isincluded in a daisy chain with the coupler circuit of the radiofrequency module. The wireless communication device can concurrentlypass two indications of radio frequency power in opposing directions inthe daisy chain.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the innovations have been described herein. It isto be understood that not necessarily all such advantages may beachieved in accordance with any particular embodiment. Thus, theinnovations may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other advantages as may be taught or suggestedherein.

The present disclosure relates to U.S. Patent Application No. [AttorneyDocket SKYWRKS.1131A1], titled “RADIO FREQUENCY SYSTEM ARRANGED TO PASSCOUPLED POWER,” filed on even date herewith, the entire disclosure ofwhich is hereby incorporated by reference herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this disclosure will now be described, by way ofnon-limiting example, with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of one example of a communication network.

FIG. 2A is a schematic diagram of one example of a communication linkusing carrier aggregation.

FIG. 2B illustrates various examples of uplink carrier aggregation forthe communication link of FIG. 2A.

FIG. 3 is a diagram of an example dual connectivity network topology.

FIG. 4A is a schematic diagram of a portion of a radio frequency modulewith a bidirectional daisy chain coupler interface according to anembodiment.

FIG. 4B is a schematic diagram of a portion of a radio frequency modulewith a bidirectional daisy chain coupler interface according to anembodiment.

FIG. 5 is a schematic diagram of a radio frequency coupler and a couplerswitching circuit according to an embodiment.

FIG. 6A is a schematic diagram of a radio frequency system with abidirectional daisy chain of coupler switching circuits for dualfeedback receiver inputs according to an embodiment.

FIG. 6B is a schematic diagram of the radio frequency system of FIG. 6Ain a state where two radio frequency modules are actively transmitting.

FIG. 7A is a schematic diagram of a radio frequency system with abidirectional daisy chain of coupler switching circuits for a singlefeedback receiver input according to an embodiment.

FIG. 7B is a schematic diagram of the radio frequency system of FIG. 7Ain a state where two radio frequency modules are actively transmitting.

FIG. 8 is a schematic diagram of a radio frequency system with abidirectional daisy chain of coupler switching circuits coupled to asingle feedback receiver input via a switch according to an embodiment.

FIG. 9 is a schematic diagram of a portion of a radio frequency modulewith a bidirectional daisy chain coupler interface for coupled powersignals with direct current and radio frequency components according toan embodiment.

FIG. 10 is a schematic diagram of an example radio frequency passcircuit electrically connected between input/output ports of the radiofrequency module of FIG. 9 according to an embodiment.

FIG. 11 is a schematic diagram of an example direct current pass circuitelectrically connected between input/output ports of the radio frequencymodule of FIG. 9 according to an embodiment.

FIG. 12 is a schematic diagram of a radio frequency system with abidirectional daisy chain of coupler switching circuits with directcurrent blocking elements between the daisy chain and dual feedbackreceiver inputs according to an embodiment.

FIG. 13 is a schematic diagram of a radio frequency system with abidirectional daisy chain of coupler switching circuits with a directcurrent blocking element between the daisy chain and a single feedbackreceiver input according to an embodiment.

FIG. 14 is a schematic diagram of one embodiment of a mobile device.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The following description of certain embodiments presents variousdescriptions of specific embodiments. However, the innovations describedherein can be embodied in a multitude of different ways, for example, asdefined and covered by the claims. In this description, reference ismade to the drawings where like reference numerals can indicateidentical or functionally similar elements. It will be understood thatelements illustrated in the figures are not necessarily drawn to scale.Moreover, it will be understood that certain embodiments can includemore elements than illustrated in a drawing and/or a subset of theelements illustrated in a drawing. Further, some embodiments canincorporate any suitable combination of features from two or moredrawings. The headings provided herein are for convenience only and arenot intended to affect the meaning or scope of the claims.

Cellular telephony radio front-ends can include feedback receivers thatare used to measure the forward and/or reflected power on a given activetransmit path for a variety of applications. A feedback receiver canalternatively be referred to as a measurement receiver. An exampleapplication includes measuring forward power and determining whetherabsolute power is above a threshold limit for a specific absorbedradiation (SAR) regulatory specification, and taking action such asreducing the power to prevent excessive radiated power amplitudes.Another example application includes measuring forward power anddetermining a relative amplitude with respect to a 50 Ohm in-factoryreference measurement made during initial calibration of a product todetermine how close the power is to the specific target power, andtaking action such as adjusting the power up and/or down to get back toa reference value. Another example application includes measuringreflected power (and perhaps with knowledge of the forward power settingor a specific measurement of the forward power as well) determining ifthe difference between forward and reflected power exceeds a thresholdand the antenna loading/de-tuning/performance has become unacceptablypoor and a different antenna should to be used for the given usecase/signal. Then the radio can perform a change in connectivity orantenna swap. Another example application includes measuring a detailedcomplex real time ratio of the forward and reflected signal in order toassess the actual complex impedance of the antenna. Based on this ratio,the radio can adjust antenna tuning settings to better setaperture/complex input impedance/both for the antenna, or to makeadjustments to the digital pre-distortion of the transmitter (DPD) tobetter optimize the linearity/efficiency/power capability into thevariable antenna load.

Such forward and/or reflected power measurements can be achieved bycoupling off a relatively small amount of the forward and/or reflectedpower and directing the coupled energy to a radio frequency (RF) paththat can be connected back to one or more feedback receiver inputs on atransceiver. The amount of coupled RF power can be relatively small soas not to incur significant insertion loss from losing useful signalenergy. A radio frequency coupler can provide a coupled power signalthat is an indication of radio frequency power.

Technical solutions for connecting a coupled RF path back to a feedbackreceiver include (1) star connection where each individual transmitcoupler is connected in parallel back to a consolidation switch and tothe appropriate feedback receiver input(s) or (2) a daisy chain whereeach coupler has a local switch to connect either (a) the local coupleror (b) an input to the output. The daisy chain path from input to outputcan be a bypass path to enable several radio frequency modules to beconnected together and eventually connect to a feedback receiver inputof a transceiver. In a daisy chain, circuitry of several radio frequencymodules are connected in series and can then be connected to a dedicatedfeedback receiver input. In certain applications, multiple clusters ofdaisy chained modules can be connected to a consolidation switch, whichthen connects to a feedback receiver input of a transceiver.

A challenge for non-stand-alone (NSA) or E-UTRAN New Radio-DualConnectivity (EN-DC) operation in Fifth Generation (5G) cellularcommunications is intermodulation distortion (IMD) and coupling/leakageof transmit carrier power when more than one transmit carrier is activeconcurrently. In such EN-DC dual connectivity for NSA operation oruplink (UL) carrier aggregation (CA) operation, leakage of a secondtransmit path power onto a first transmit path for measurement canreduce accuracy and/or limit a useful dynamic range of a feedbackreceiver. For example, isolation can be challenging when a low powerreflected power signal is being routed in the presence of a high powerblocker.

Some schemes further make flexible use of programming the supply domainsand first transmit path or second transmit path operation betweendifferent modules, in such a way that the coupled path isolation andtransmit leakage management is also flexibly programmed to provideisolation and avoid a first transmit path coupled path from goingthrough a second transmit path active module, and vice-versa. This canbe further complicated by the availability of only a single feedbackreceiver input.

Aspects of this disclosure relate to radio frequency module withinput/output ports for providing and/or passing an indication of radiofrequency power. Two input/output ports of the radio frequency modulecan be reconfigurable such that each of these input/output ports can (a)function as an input to receive a coupled power signal from anotherradio frequency module and provide the coupled power signal to the otherinput/output port, (b) function as an output to provide a coupled powersignal from another radio frequency module received at the otherinput/output port, and (c) output a coupled power signal from a radiofrequency coupler of the radio frequency module. A coupled power signalprovides an indication of radio frequency power. A forward powermeasurement or a reflected power measurement from a radio frequencycoupler, such as a directional coupler, of the radio frequency modulecan be output at either of the two input/output ports. A couplerswitching circuit can be configured to (a) enable a daisy chain tobypass from a first of the two input/output ports as an input to asecond of the two input/output ports as an output or (b) enable thedaisy chain to bypass from the second of the two input/output ports asan input to the first of the two input/output ports as an output.

Circuitry of a plurality of such radio frequency modules can beconnected together in a daisy chain. The daisy chain can be a loopbetween two different feedback receiver inputs. Coupled power from twoactively transmitting modules of the plurality of radio frequencymodules can be routed in opposite directions to an appropriaterespective feedback receiver input without overlapping or running onetransmit path coupled power through a radio frequency module withanother concurrently active transmit path for isolation and/or otherconsiderations. A coupler switching circuit in a radio frequency modulecan enable bidirectional routing for a coupled power signal generated bya radio frequency coupler of the radio frequency module. Withbidirectional routing, the coupled power signal can be routed eitherclockwise or counter-clockwise around the daisy chain back to a feedbackreceiver input.

In certain instances, a daisy chain loop including circuitry of aplurality of radio frequency modules can be connected to a single nodethat is electrically connected to a single feedback receiver input. Bymaintaining programmable bidirectionality of the coupled power aroundthe daisy chain loop, a first transmit path coupled power signal can berouted to the single feedback receiver input without passing through aradio frequency module with a concurrently active second transmit path.Similarly, the second transmit path coupled power signal can be routedto the single feedback receiver input without passing through a radiofrequency module with the concurrently active first transmit path.

Radio frequency modules and radio frequency systems disclosed herein canachieve a variety of advantages over other technical solutions. Forexample, a daisy chain can be connected to a feedback receiver inputwithout a consolidation switch external to radio frequency modules ofthe daisy chain. Technical solutions disclosed herein can scale with anarbitrary number of connected radio frequency modules. There can be nosignificant isolation issues between two concurrently active transmitpaths because a coupled power signal from one transmit path can berouted away from a module with another concurrently active transmitpath. Technical solutions disclosed herein can be realized in arelatively small physical area and can reduce and/or minimize longroutes on a phone board from a radio frequency module positionedrelatively far away from a feedback receiver. Technical solutionsdisclosed herein can implement daisy chaining for coupled power signalswith simplified overhead, control, and/or timing.

5G Technology and Example Communication Network

The International Telecommunication Union (ITU) is a specialized agencyof the United Nations (UN) responsible for global issues concerninginformation and communication technologies, including the shared globaluse of radio spectrum.

The 3rd Generation Partnership Project (3GPP) is a collaboration betweengroups of telecommunications standard bodies across the world, such asthe Association of Radio Industries and Businesses (ARIB), theTelecommunications Technology Committee (TTC), the China CommunicationsStandards Association (CCSA), the Alliance for TelecommunicationsIndustry Solutions (ATIS), the Telecommunications Technology Association(TTA), the European Telecommunications Standards Institute (ETSI), andthe Telecommunications Standards Development Society, India (TSDSI).

Working within the scope of the ITU, 3GPP develops and maintainstechnical specifications for a variety of mobile communicationtechnologies, including, for example, second generation (2G) technology(for instance, Global System for Mobile Communications (GSM) andEnhanced Data Rates for GSM Evolution (EDGE)), third generation (3G)technology (for instance, Universal Mobile Telecommunications System(UMTS) and High Speed Packet Access (HSPA)), and fourth generation (4G)technology (for instance, Long Term Evolution (LTE) and LTE-Advanced).

The technical specifications controlled by 3GPP can be expanded andrevised by specification releases, which can span multiple years andspecify a breadth of new features and evolutions.

In one example, 3GPP introduced carrier aggregation (CA) for LTE inRelease 10. Although initially introduced with two downlink carriers,3GPP expanded carrier aggregation in Release 14 to include up to fivedownlink carriers and up to three uplink carriers. Other examples of newfeatures and evolutions provided by 3GPP releases include, but are notlimited to, License Assisted Access (LAA), enhanced LAA (eLAA),Narrowband Internet of things (NB-IOT), Vehicle-to-Everything (V2X), andHigh Power User Equipment (HPUE).

3GPP introduced Phase 1 of fifth generation (5G) technology in Release15, and is currently in the process of developing Phase 2 of 5Gtechnology in Release 16. Subsequent 3GPP releases will further evolveand expand 5G technology. 5G technology is also referred to herein as 5GNew Radio (NR).

5G NR supports or plans to support a variety of features, such ascommunications over millimeter wave spectrum, beamforming capability,high spectral efficiency waveforms, low latency communications, multipleradio numerology, and/or non-orthogonal multiple access (NOMA). Althoughsuch RF functionalities offer flexibility to networks and enhance userdata rates, supporting such features can pose a number of technicalchallenges.

The teachings herein are applicable to a wide variety of communicationsystems, including, but not limited to, communication systems usingadvanced cellular technologies, such as LTE-Advanced, LTE-Advanced Pro,and/or 5G NR.

FIG. 1 is a schematic diagram of one example of a communication network10. The communication network 10 includes a macro cell base station 1, amobile device 2, a small cell base station 3, and a stationary wirelessdevice 4. Embodiments disclosed herein can be implemented in thecommunication network 10, for example.

The illustrated communication network 10 of FIG. 1 supportscommunications using a variety of technologies, including, for example,4G LTE, 5G NR, and wireless local area network (WLAN), such as WiFi. Inthe communication network 10, dual connectivity can be implemented withconcurrent 4G LTE and 5G NR communication with the mobile device 2.Although various examples of supported communication technologies areshown, the communication network 10 can be adapted to support a widevariety of communication technologies.

Various communication links of the communication network 10 have beendepicted in FIG. 1. The communication links can be duplexed in a widevariety of ways, including, for example, using frequency-divisionduplexing (FDD) and/or time-division duplexing (TDD). FDD is a type ofradio frequency communications that uses different frequencies fortransmitting and receiving signals. FDD can provide a number ofadvantages, such as high data rates and low latency. In contrast, TDD isa type of radio frequency communications that uses about the samefrequency for transmitting and receiving signals, and in which transmitand receive communications are switched in time. TDD can provide anumber of advantages, such as efficient use of spectrum and variableallocation of throughput between transmit and receive directions.

As shown in FIG. 1, the mobile device 2 communicates with the macro cellbase station 1 over a communication link that uses a combination of 4GLTE and 5G NR technologies. The mobile device 2 also communications withthe small cell base station 3. In the illustrated example, the mobiledevice 2 and small cell base station 3 communicate over a communicationlink that uses 5G NR, 4G LTE, and WiFi technologies. In certainimplementations, enhanced license assisted access (eLAA) is used toaggregate one or more licensed frequency carriers (for instance,licensed 4G LTE and/or 5G NR frequencies), with one or more unlicensedcarriers (for instance, unlicensed WiFi frequencies).

In certain implementations, the mobile device 2 communicates with themacro cell base station 2 and the small cell base station 3 using 5G NRtechnology over one or more frequency bands that within Frequency Range1 (FR1) and/or over one or more frequency bands that are above FR1. Theone or more frequency bands within FR1 can be less than 6 GHz. Forexample, wireless communications can utilize FR1, Frequency Range 2(FR2), or a combination thereof. In one embodiment, the mobile device 2supports a HPUE power class specification.

The illustrated small cell base station 3 also communicates with astationary wireless device 4. The small cell base station 3 can be used,for example, to provide broadband service using 5G NR technology. Incertain implementations, the small cell base station 3 communicates withthe stationary wireless device 4 over one or more millimeter wavefrequency bands in the frequency range of 30 GHz to 300 GHz and/or uppercentimeter wave frequency bands in the frequency range of 24 GHz to 30GHz.

In certain implementations, the small cell base station 3 communicateswith the stationary wireless device 4 using beamforming. For example,beamforming can be used to focus signal strength to overcome pathlosses, such as high loss associated with communicating over millimeterwave frequencies.

The communication network 10 of FIG. 1 includes the macro cell basestation 1 and the small cell base station 3. In certain implementations,the small cell base station 3 can operate with relatively lower power,shorter range, and/or with fewer concurrent users relative to the macrocell base station 1. The small cell base station 3 can also be referredto as a femtocell, a picocell, or a microcell.

Although the communication network 10 is illustrated as including twobase stations, the communication network 10 can be implemented toinclude more or fewer base stations and/or base stations of other types.As shown in FIG. 1, base stations can communicate with one another usingwireless communications to provide a wireless backhaul. Additionally oralternatively, base stations can communicate with one another usingwired and/or optical links.

The communication network 10 of FIG. 1 is illustrated as including onemobile device and one stationary wireless device. The mobile device 2and the stationary wireless device 4 illustrate two examples of userdevices or user equipment (UE). Although the communication network 10 isillustrated as including two user devices, the communication network 10can be used to communicate with more or fewer user devices and/or userdevices of other types. For example, user devices can include mobilephones, tablets, laptops, IoT devices, wearable electronics, and/or awide variety of other communications devices.

User devices of the communication network 10 can share available networkresources (for instance, available frequency spectrum) in a wide varietyof ways.

In one example, frequency division multiple access (FDMA) is used todivide a frequency band into multiple frequency carriers. Additionally,one or more carriers are allocated to a particular user. Examples ofFDMA include, but are not limited to, single carrier FDMA (SC-FDMA) andorthogonal FDMA (OFDMA). OFDMA is a multicarrier technology thatsubdivides the available bandwidth into multiple mutually orthogonalnarrowband subcarriers, which can be separately assigned to differentusers.

Other examples of shared access include, but are not limited to, timedivision multiple access (TDMA) in which a user is allocated particulartime slots for using a frequency resource, code division multiple access(CDMA) in which a frequency resource is shared amongst different usersby assigning each user device a unique code, space-divisional multipleaccess (SDMA) in which beamforming is used to provide shared access byspatial division, and non-orthogonal multiple access (NOMA) in which thepower domain is used for multiple access. For example, NOMA can be usedto serve multiple user devices at the same frequency, time, and/or code,but with different power levels.

Enhanced mobile broadband (eMBB) refers to technology for growing systemcapacity of LTE networks. For example, eMBB can refer to communicationswith a peak data rate of at least 10 Gbps and a minimum of 100 Mbps foreach user device. Ultra-reliable low latency communications (uRLLC)refers to technology for communication with very low latency, forinstance, less than 2 milliseconds. uRLLC can be used formission-critical communications such as for autonomous driving and/orremote surgery applications. Massive machine-type communications (mMTC)refers to low cost and low data rate communications associated withwireless connections to everyday objects, such as those associated withInternet of Things (IoT) applications.

The communication network 10 of FIG. 1 can be used to support a widevariety of advanced communication features, including, but not limitedto eMBB, uRLLC, and/or mMTC.

A peak data rate of a communication link (for instance, between a basestation and a user device) depends on a variety of factors. For example,peak data rate can be affected by channel bandwidth, modulation order, anumber of component carriers, and/or a number of antennas used forcommunications.

For instance, in certain implementations, a data rate of a communicationlink can be about equal to M*B*log₂(1+S/N), where M is the number ofcommunication channels, B is the channel bandwidth, and S/N is thesignal-to-noise ratio (SNR).

Accordingly, data rate of a communication link can be increased byincreasing the number of communication channels (for instance,transmitting and receiving using multiple antennas), using widerbandwidth (for instance, by aggregating carriers), and/or improving SNR(for instance, by increasing transmit power and/or improving receiversensitivity).

5G NR communication systems can employ a wide variety of techniques forenhancing data rate and/or communication performance.

Carrier Aggregation

FIG. 2A is a schematic diagram of one example of a communication linkusing carrier aggregation. Carrier aggregation can be used to widenbandwidth of the communication link by supporting communications overmultiple frequency carriers, thereby increasing user data rates andenhancing network capacity by utilizing fragmented spectrum allocations.Carrier aggregation can present technical challenges for measuring powerof individual carriers. Radio frequency systems disclosed herein canmeasure power associated with one or more transmit paths in carrieraggregation applications. Embodiments disclosed herein can beimplemented in carrier aggregation applications.

In the illustrated example, the communication link is provided between abase station 21 and a mobile device 22. As shown in FIG. 2A, thecommunications link includes a downlink channel used for RFcommunications from the base station 21 to the mobile device 22, and anuplink channel used for RF communications from the mobile device 22 tothe base station 21.

Although FIG. 2A illustrates carrier aggregation in the context of FDDcommunications, carrier aggregation can also be used for TDDcommunications.

In certain implementations, a communication link can provideasymmetrical data rates for a downlink channel and an uplink channel.For example, a communication link can be used to support a relativelyhigh downlink data rate to enable high speed streaming of multimediacontent to a mobile device, while providing a relatively slower datarate for uploading data from the mobile device to the cloud.

In the illustrated example, the base station 21 and the mobile device 22communicate via carrier aggregation, which can be used to selectivelyincrease bandwidth of the communication link. Carrier aggregationincludes contiguous aggregation, in which contiguous carriers within thesame operating frequency band are aggregated. Carrier aggregation canalso be non-contiguous, and can include carriers separated in frequencywithin a common band or in different bands.

In the example shown in FIG. 2A, the uplink channel includes threeaggregated component carriers f_(UL1), f_(UL2), and f_(UL3).Additionally, the downlink channel includes five aggregated componentcarriers f_(DL1), f_(DL2), f_(DL3), f_(DL4), and f_(DL5). Although oneexample of component carrier aggregation is shown, more or fewercarriers can be aggregated for uplink and/or downlink. Moreover, anumber of aggregated carriers can be varied over time to achieve desireduplink and downlink data rates.

For example, a number of aggregated carriers for uplink and/or downlinkcommunications with respect to a particular mobile device can changeover time. For example, the number of aggregated carriers can change asthe device moves through the communication network and/or as networkusage changes over time.

FIG. 2B illustrates various examples of uplink carrier aggregation forthe communication link of FIG. 2A. FIG. 2B includes a first carrieraggregation scenario 31, a second carrier aggregation scenario 32, and athird carrier aggregation scenario 33, which schematically depict threetypes of carrier aggregation.

The carrier aggregation scenarios 31-33 illustrate different spectrumallocations for a first component carrier f_(UL1), a second componentcarrier f_(UL2), and a third component carrier f_(UL3). Although FIG. 2Bis illustrated in the context of aggregating three component carriers,carrier aggregation can be used to aggregate more or fewer carriers.Moreover, although illustrated in the context of uplink, the aggregationscenarios are also applicable to downlink.

The first carrier aggregation scenario 31 illustrates intra-bandcontiguous carrier aggregation, in which component carriers that areadjacent in frequency and in a common frequency band are aggregated. Forexample, the first carrier aggregation scenario 31 depicts aggregationof component carriers f_(UL1), f_(UL2), and f_(UL3) that are contiguousand located within a first frequency band BAND1.

With continuing reference to FIG. 2B, the second carrier aggregationscenario 32 illustrates intra-band non-continuous carrier aggregation,in which two or more components carriers that are non-adjacent infrequency and within a common frequency band are aggregated. Forexample, the second carrier aggregation scenario 32 depicts aggregationof component carriers f_(UL1), f_(UL2), and f_(UL3) that arenon-contiguous, but located within a first frequency band BAND1.

The third carrier aggregation scenario 33 illustrates inter-bandnon-contiguous carrier aggregation, in which component carriers that arenon-adjacent in frequency and in multiple frequency bands areaggregated. For example, the third carrier aggregation scenario 33depicts aggregation of component carriers f_(UL1) and f_(UL2) of a firstfrequency band BAND1 with component carrier f_(UL3) of a secondfrequency band BAND2.

With reference to FIGS. 2A and 2B, the individual component carriersused in carrier aggregation can be of a variety of frequencies,including, for example, frequency carriers in the same band or inmultiple bands. Additionally, carrier aggregation is applicable toimplementations in which the individual component carriers are of aboutthe same bandwidth as well as to implementations in which the individualcomponent carriers have different bandwidths.

Certain communication networks allocate a particular user device with aprimary component carrier (PCC) or anchor carrier for uplink and a PCCfor downlink. Additionally, when the mobile device communicates using asingle frequency carrier for uplink or downlink, the user devicecommunicates using the PCC. To enhance bandwidth for uplinkcommunications, the uplink PCC can be aggregated with one or more uplinksecondary component carriers (SCCs). Additionally, to enhance bandwidthfor downlink communications, the downlink PCC can be aggregated with oneor more downlink SCCs.

In certain implementations, a communication network provides a networkcell for each component carrier. Additionally, a primary cell canoperate using a PCC, while a secondary cell can operate using a SCC. Theprimary and secondary cells may have different coverage areas, forinstance, due to differences in frequencies of carriers and/or networkenvironment.

License assisted access (LAA) refers to downlink carrier aggregation inwhich a licensed frequency carrier associated with a mobile operator isaggregated with a frequency carrier in unlicensed spectrum, such asWiFi. LAA employs a downlink PCC in the licensed spectrum that carriescontrol and signaling information associated with the communicationlink, while unlicensed spectrum is aggregated for wider downlinkbandwidth when available. LAA can operate with dynamic adjustment ofsecondary carriers to avoid WiFi users and/or to coexist with WiFiusers. Enhanced license assisted access (eLAA) refers to an evolution ofLAA that aggregates licensed and unlicensed spectrum for both downlinkand uplink.

Dual Connectivity

With the introduction of the 5G NR air interface standards, 3GPP hasallowed for the simultaneous operation of 5G and 4G standards in orderto facilitate the transition. This mode can be referred to asNon-Stand-Alone (NSA) operation or E-UTRAN New Radio-Dual Connectivity(EN-DC) and can involve both 4G and 5G carriers being simultaneouslytransmitted from a user equipment (UE). EN-DC can present technicalchallenges for measuring power associated with individual transmitpaths. Radio frequency systems disclosed herein can measure powerassociated with one or more transmit paths in dual connectivityapplications. Embodiments disclosed herein can be implemented in dualconnectivity applications.

In certain EN-DC applications, dual connectivity NSA involves overlaying5G systems onto an existing 4G core network. For dual connectivity insuch applications, the control and synchronization between the basestation and the UE can be performed by the 4G network while the 5Gnetwork is a complementary radio access network tethered to the 4Ganchor. The 4G anchor can connect to the existing 4G network with theoverlay of 5G data/control.

FIG. 3 is a diagram of an example dual connectivity network topology.This architecture can leverage LTE legacy coverage to ensure continuityof service delivery and the progressive rollout of 5G cells. A UE 30 cansimultaneously transmit dual uplink LTE and NR carriers. The UE 30 cantransmit an uplink LTE carrier Tx1 to the eNB 31 while transmitting anuplink NR carrier Tx2 to the gNB 32 to implement dual connectivity. Anysuitable combination of uplink carriers Tx1, Tx2 and/or downlinkcarriers Rx1, Rx2 can be concurrently transmitted via wireless links inthe example network topology of FIG. 3. The eNB 31 can provide aconnection with a core network, such as an Evolved Packet Core (EPC).The gNB 32 can communicate with the core network via the eNB 31. Controlplane data can be wirelessly communicated between the UE 30 and eNB 31.The eNB 31 can also communicate control plane data with the gNB 32.

In the example dual connectivity topology of FIG. 3, any suitablecombinations of standardized bands and radio access technologies (e.g.,FDD, TDD, SUL, SDL) can be wirelessly transmitted and received. This canpresent technical challenges related to having multiple separate radiosand bands functioning in the UE 30. With a TDD LTE anchor point, networkoperation may be synchronous, in which case the operating modes can beconstrained to Tx1/Tx2 and Rx1/Rx2, or asynchronous which can involveTx1/Tx2, Tx1/Rx2, Rx1/Tx2, or Rx1/Rx2. When the LTE anchor is afrequency division duplex (FDD) carrier, the TDD/FDD inter-bandoperation can involve simultaneous Tx1/Rx1/Tx2 and Tx1/Rx1/Rx2.

Radio Frequency Modules with Coupler Switching Circuit and Daisy ChainArchitecture of Coupler Switching Circuits

Radio frequency modules disclosed herein include coupler switchingcircuits arranged to bidirectionally pass a coupled power signal betweeninput/output ports of a radio frequency module. Coupler switchingcircuits in a plurality of modules can be arranged in a daisy chain. Acoupler switching circuit of an individual radio frequency module canprovide a coupled power signal from a radio frequency coupler to aninput/output port to cause the coupled power signal to propagate in aparticular direction through the daisy chain to a feedback receiverinput port. The coupler switching circuit can cause the coupled powersignal to propagate in opposite directions though the daisy chain indifferent states.

Daisy chained coupler switching circuit architectures disclosed hereincan be scalable and achieve high isolation between coupled power signalsassociated with different transmit paths. In some instances, daisychained coupler switching circuit architectures disclosed herein can beimplemented without a switch external to the radio frequency modulesbetween the daisy chain and an input of a feedback receiver. The couplerswitching circuits and related daisy chains can be implemented inapplications where two or more transmit paths are concurrently active,such as carrier aggregation applications and/or dual connectivityapplications.

FIG. 4A is a schematic diagram of a portion of a radio frequency module40 with a bidirectional daisy chain coupler interface according to anembodiment. The radio frequency module 40 can be implemented with oneless contact (e.g., pin) compared to some other technical solutions. Theradio frequency module 40 can improve isolation of coupled powersignals. The radio frequency module 40 can be implemented withoutexternal switching for a daisy chain in certain applications. Asillustrated, the radio frequency module 40 includes a multi-throw switch41, radio frequency couplers 42A and 42B, notch filters 43A and 43B,termination and output switches 44A and 44B, termination impedances 45A,45B, 45C, 45D, a coupled power output switch 46, and a bypass switch 47.In the radio frequency module 40, the termination and output switches44A and 44B, the coupled power output switch 46, and the bypass switch47 together implement a coupler switching circuit.

A bidirectional daisy chain coupler interface of the radio frequencymodule 40 enables two input/output ports CPL1 and CPL2 to each be (a) anoutput for a coupled power signal generated by a radio frequency coupler42A or 42B of the radio frequency module 40, (b) an input for receivinga coupled power signal from another module, or (c) an output for passinga coupled power signal from another module received at the otherinput/output port.

For example, the coupled power output switch 46 can electrically connecteither radio frequency coupler 42A or radio frequency coupler 42B toeither a first input/output port CPL1 or a second input/output portCPL2. This can enable the radio frequency module 40 to output coupledradio frequency power to propagate in either direction in a daisy chain.The coupled power output switch 46 can provide either a forward coupledpower signal or a reverse coupled power signal depending on a state of atermination and output switch 44A or 44B.

The bypass switch 47 can enable a coupled power signal received at thefirst input/output port CPL1 to be passed to the second input/outputport CPL2. Similarly, the bypass switch 47 can enable a coupled powersignal received at the second input/output port CPL2 to be passed to thefirst input/output port CPL1. Accordingly, the bidirectional daisy chaincoupler interface of the radio frequency module 40 can implement abidirectional pass through of coupled power signals. The input/outputports CPL1 and CPL2 can be implemented by any suitable contacts, such asone or more pins, one or more pads, one or more bumps, the like, or anysuitable combination thereof.

The multi-throw switch 41 can be a multi-throw double-pole switch asillustrated. The multi-throw switch 41 can receive a radio frequencysignal for transmission. The radio frequency signal can be generated bya power amplifier of the radio frequency module 40. In certainapplications, different power amplifiers can be coupled to respectivenotch filters 43A and 43B via the multi-throw switch 41. The multi-throwswitch 41 can be coupled to a plurality of transmit signal paths, whichcan include different filters. The multi-throw switch 41 can provide anoutput from a selected transmit path to the first radio frequencycoupler 42A. The multi-throw switch 41 can provide an output from aselected transmit path to the second radio frequency coupler 42B.

The first radio frequency coupler 42A can couple a relatively smallamount of forward or reflected power propagating between the multi-throwswitch 41 to the notch filter 43A. The reflected power can be referredto as reverse power. The first termination and output switch 44A canconnect one port of the first radio frequency coupler 42A to the coupledpower output switch 46 and another port to one of the terminationimpedances 45A or 45B. The termination impedances 45A, 45B, 45C, and 45Dcan each include a resistor.

The first termination and output switch 44A can be set to a first statecorresponding to providing a forward power measurement or a second statecorresponding to providing a reverse power measurement. In FIG. 4A, thefirst termination and output switch 44A is shown in the first statewhere the termination impedance 45B is connected to a port of the radiofrequency coupler 42A. The first termination and output switch 44B cantoggle between the first state and the second state. In the secondstate, the port of the first radio frequency coupler 42A illustrated inFIG. 4A as being connected to the termination impedance 45B is insteadconnected to the coupled power output switch 46 and the port of thefirst radio frequency coupler 42A illustrated in FIG. 4A as beingconnected to the coupled power output switch 46 is instead connectedtermination impedance 45A.

The second radio frequency coupler 42B can couple a relatively smallamount of forward or reflected power propagating between the multi-throwswitch 41 to the notch filter 43B. The second termination and outputswitch 44B can connect one port of the second radio frequency coupler42B to the coupled power output switch 46 and another port to one of thetermination impedances 45C or 45D.

The second termination and output switch 44B can be set to a first statecorresponding to providing a forward power measurement or a second statecorresponding to providing a reverse power measurement. In FIG. 4A, thesecond termination and output switch 44B is shown in the second state.The second termination and output switch 44B can toggle between thefirst state for providing forward coupled power and the second state forproviding reflected coupled power.

The coupled power output switch 46 can electrically connect the firsttermination and output switch 44A the first input/output port CPL1 orthe second input/output port CPL 2. The coupled power output switch 46can electrically connect the second termination and output switch 44B tothe first input/output port CPL1 or the second input/output port CPL 2.In certain instances, the coupled power output switch 46 can provide asingle coupled power signal to either the input/output port CPL1 or theinput/output port CPL2. The coupled power output switch 46 can providecoupled power signals from radio frequency couplers 42A and 42B todifferent input/output ports CPL1 and CPL2 concurrently in someapplications.

The bypass switch 47 can provide a bypass path between the firstinput/output port CPL1 and the second input/output port CPL2. A coupledpower signal received at either one of these ports can be provided tothe other one of these ports. The bypass switch 47 can be turned offwhen the radio frequency module 40 is providing a coupled power signalfrom a radio frequency coupler 42A or 42B to an input/output port CPL1or CPL2. When the bypass switch 47 is turned off, the input/output portsCPL1 and CPL2 can be electrically isolated from each other.

FIG. 4B is a schematic diagram of a portion of a radio frequency module48 with a bidirectional daisy chain coupler interface according to anembodiment. The radio frequency module 48 can be implemented with fewercontacts compared to some other technical solutions and/or improveisolation of coupled power signals. The radio frequency module 48 can beimplemented without external switching for a daisy chain in certainapplications. As illustrated, the radio frequency module 48 includes apower amplifier 36, a filter 38, a multi-throw switch 41′, a radiofrequency coupler 42 connected to a termination impedance 45, and acoupler switching circuit 49, and a bypass switch 47. The couplerswitching circuit 49 can be implemented in accordance with any suitableprinciples and advantages disclosed herein. FIG. 4B illustrates that theradio frequency coupler 42 and the coupler switching circuit 49 can beincluded in a radio frequency module that also includes the poweramplifier 36. One or more circuit elements can be included in a signalpath between the power amplifier 36 and the radio frequency coupler 42.For example, as illustrated, the filter 38 and switch 41′ can be in asignal path between the power amplifier 36 and the radio frequencycoupler 42. The coupled power signal generated by the radio frequencycoupler 42 can be indicative of power of a radio frequency signalgenerated by the power amplifier 36.

FIG. 5 is a schematic diagram of a radio frequency coupler 42 and acoupler switching circuit 50 according to an embodiment. The couplerswitching circuit 50 includes a plurality of switches 51, 52, 53, 54,55, 56, 57, 58, and 59. The switches 51 to 59 of the coupler switchingcircuit 50 can be controlled by a control circuit to provide variousconnections between the radio frequency coupler 42 and the input/outputports CPL1 and CPL2 and between the input/output ports CPL1 and CPL2.FIG. 5 also illustrates that termination impedances 45A and 45B can betunable. Any of the termination impedances disclosed herein can betunable as suitable.

The coupler switching circuit 50 can provide a forward coupled powersignal to the first input/output port CPL1. In this mode, the switches51, 52, and 55 are On and the other illustrated switches of the couplerswitching circuit 50 are Off. The coupler switching circuit 50 canprovide a reverse coupled power signal to the first input/output portCPL1. In this mode, the switches 53, 54, and 57 are On and the otherillustrated switches of the coupler switching circuit 50 are Off.

The coupler switching circuit 50 can provide a forward coupled powersignal to the first input/output port CPL 2. In this mode, the switches51, 52, and 56 are On and the other illustrated switches of the couplerswitching circuit 50 are Off. The coupler switching circuit 50 canprovide a reverse coupled power signal to the first input/output portCPL2. In this mode, the switches 53, 54, and 58 are On and the otherillustrated switches of the coupler switching circuit 50 are Off.

The coupler switching circuit 50 can pass a coupled power signal fromthe first input/output port CPL1 to the second input/output port CPL2.Similarly, the coupler switching circuit 50 can pass a coupled powersignal from the second input/output port CPL1 to the first input/outputport CPL2. In the modes where a coupled power signal is passed from oneinput/output port to the other, the switch 59 is On and the otherillustrated switches of the coupler switching circuit 50 are Off.

Table 1 below summarizes states of the switches 51 to 59 of the couplerswitching circuit 50 for these modes. In Table 1, FWD CPL representsforward coupled power and REV CPL represents reverse coupled power.

TABLE 1 Mode/Switch 51/52 53/54 55 56 57 58 59 FWD CPL −> CPL1 On Off OnOff Off Off Off REV CPL −> CPL1 Off On Off Off On Off Off FWD CPL −>CPL2 On Off Off On Off Off Off REV CPL −> CPL2 Off On Off Off Off On OffCPL1 −> CPL2 Off Off Off Off Off Off On CPL2 −> CPL1 Off Off Off Off OffOff On

FIG. 6A is a schematic diagram of a radio frequency system 60 with abidirectional daisy chain of coupler switching circuits for dualfeedback receiver inputs according to an embodiment. The illustrateddaisy chain is arranged in a loop between two feedback receiver inputs.A coupler switching circuit can bidirectionally pass a coupled powersignal through the daisy chain to either of the two feedback receiverinputs. A coupled power signal associated with a first transmit path canbe routed through the daisy chain to the feedback receiver withoutpassing through a radio frequency module with a second transmit paththat is concurrently active. Similarly, a coupled power signalassociated with the transmit path can be routed through the daisy chainto the feedback receiver without passing through a radio frequencymodule that includes the first transmit path when the first and secondtransmit paths are both active. High isolation can be achieved betweencoupled power signals regardless of a number of modules, a number ofsupply domains, or how transmit paths are connected.

As illustrated, the radio frequency system 60 includes a plurality ofradio frequency modules 61, 62, 63, 64, 65, and 66 and a transceiver 67.The radio frequency modules 61, 62, 63, 64, 65, and 66 can beimplemented with any suitable principles and advantages disclosed withreference to the radio frequency module 40 of FIG. 4A and/or the radiofrequency module 48 of FIG. 4B. Each of the radio frequency modules 61to 66 can include a coupler switching circuit, where the couplerswitching circuits are together arranged in a daisy chain. The daisychain can form a loop between feedback receiver inputs FB Rx1 and FB Rx2of the transceiver 67. In the daisy chain, input/output ports of radiofrequency modules are electrically connected to each other external tothe radio frequency modules. The coupler switching circuits can beimplemented in accordance with any suitable principles and advantagesdiscussed with reference to FIGS. 4 and/or 5. Some or all of the radiofrequency modules 61 to 66 can include one or more transmit paths. Twoor more of the radio frequency modules 61 to 66 can include transmitpaths that are concurrently active. The transmit paths can beconcurrently active in a carrier aggregation application and/or a dualconnectivity application.

In certain instances, radio frequency modules 61 to 66 can each havecoupler switching circuits with any suitable combination of featuresdisclosed herein. According to some other instances, radio frequencymodules 61 and 66 at ends of the daisy chain can have simplified couplerswitching circuits that are unidirectional. In some applications, thedaisy chain can include one or more one or more radio frequency modules(e.g., one or more diversity receive modules) arranged to pass a coupledpower signal between two input/output ports without the functionality toprovide a coupled power signal generated by the radio frequency moduleto either of the two input/output ports.

In physical layout, the radio frequency modules 61 to 66 can be arrangedto reduce and/or minimize the length of routes (1) between input/outputports of different radio frequency modules and (2) between input/outputports of the radio frequency modules at the ends of the daisy chain tothe feedback receiver inputs. Accordingly, all of these routes can berelatively short in certain physical layouts. This can reduce and/orminimize parasitic capacitance associated with such routes.

The transceiver 67 includes a feedback receiver. The transceiver 67 canbe implemented on an integrated circuit. The feedback receiver canprocess coupled power signals from the radio frequency modules 61 to 66.The feedback receiver can process a plurality of coupled power signalsconcurrently. The feedback receiver can include one or more receivepaths that each include any suitable circuitry arranged to process acoupled power signal. For example, a receive path of a feedback receivercan include a low noise amplifier, a mixer, a filter, and ananalog-to-digital converter. One or more adjustments to a transmit pathcan be performed in response to an output of the receive path of thefeedback receiver.

FIG. 6B is a schematic diagram of the radio frequency system 60 of FIG.6A in a state where two radio frequency modules are activelytransmitting. In FIG. 6B, the radio frequency modules 62 and 64 areconcurrently transmitting. The first transmitting radio frequency module62 can provide a coupled power signal at a first input/output port CPL1.For example, a coupler switching circuit of the first transmitting radiofrequency module 62 can electrically connect a radio frequency couplerof the first transmitting radio frequency module 62 to the firstinput/output port CPL1 of the first transmitting radio frequency module62. The second transmitting radio frequency module 64 can provide acoupled power signal at a second input/output port CPL2. For example, acoupler switching circuit of the second transmitting radio frequencymodule 64 can electrically connect a radio frequency coupler of thesecond transmitting radio frequency module 64 to the second input/outputport CPL2 of the second transmitting radio frequency module 64.

As illustrated, the coupled power signals from the transmitting radiofrequency modules 62 and 64 can propagate in different directionsthrough the daisy chain to different respective feedback receiver inputsFB Rx1 and FB Rx2. The different directions are opposite directions asillustrated in FIG. 6B. Accordingly, in the state shown in FIG. 6B,coupled power signals do not propagate through another activetransmitting radio frequency module in the daisy chain. This can achievehigh isolation. In the state shown in FIG. 6B, coupled power signals donot propagate through coupler switching circuits of the radio frequencymodule 63.

FIG. 7A is a schematic diagram of a radio frequency system 70 with abidirectional daisy chain of coupler switching circuits for a singlefeedback receiver input according to an embodiment. In the radiofrequency system 70, a transceiver 67′ includes one feedback receiverinput FB Rx. The daisy chain of coupler switching circuits in the radiofrequency system 70 is like the daisy chain in the radio frequencysystem 60 except that ends of the daisy chain connect at T connection 72in the radio frequency system 70. The T connection 72 can be referred toas a T junction. The daisy chain of the radio frequency system 70connects to a single feedback receiver input FB Rx. The daisy chainillustrated in FIG. 7A is implemented without switching external to theradio frequency modules 61 to 66.

FIG. 7B is a schematic diagram of the radio frequency system 70 of FIG.7A in a state where two radio frequency modules are activelytransmitting. In FIG. 7B, the radio frequency modules 62 and 64 areconcurrently transmitting. As illustrated, the coupled power signalsfrom the transmitting radio frequency modules 62 and 64 can propagate indifferent directions through the daisy chain to the T connection 72.Accordingly, in the state shown in FIG. 7B, coupled power signals froman active transmitting radio frequency module do not propagate throughanother active transmitting radio frequency module in the daisy chain.This can achieve high isolation.

In some applications, a coupled power signal from the first activelytransmitting radio frequency module 62 can propagate through the daisychain at a different time than the coupled power signal form the secondactively transmitting radio frequency module 64 in the radio frequencysystem 70. In such applications, a coupled power signal from the firstactively transmitting radio frequency module 62 received by a feedbackreceiver does not propagate through the second actively transmittingradio frequency module 64.

In certain applications, coupled power signals from the first activelytransmitting radio frequency module 62 and the second activelytransmitting radio frequency module 64 can propagate through the daisychain concurrently in the radio frequency system 70. In suchapplications, the feedback receiver can separate the coupled powersignals from the different actively transmitting radio frequency modules62 and 64 for further separate processing. For example, a diplexer ofthe transceiver 67′ can separate such coupled power signals

FIG. 8 is a schematic diagram of a radio frequency system 80 with abidirectional daisy chain of coupler switching circuits coupled to asingle feedback receiver input via a switch 82 according to anembodiment. The switch 82 can selectively electrically connect one endof the daisy chain to the feedback receiver input port FB Rx of thetransceiver 67′. The switch 82 can selectively electrically connect aport CPL of another radio frequency module 81 to the feedback receiverinput port FB Rx.

The principles and advantages disclosed herein can be implemented inradio frequency systems where any suitable number of daisy chains ofcoupler switching circuits and any suitable number of ports ofindividual radio frequency modules can be electrically connected to afeedback receiver. For example, in certain applications, two or moredaisy chains of coupler switching circuits can be electrically connectedto a feedback receiver. As another example, in some applications, one ormore daisy chains of coupler switching circuits and two or moreindividual radio frequency modules can be electrically connected to afeedback receiver. As one more example, in various applications, two ormore daisy chains of coupler switching circuits can each be coupled to adifferent feedback receiver port and/or a different feedback receiver.

FIG. 9 is a schematic diagram of a portion of a radio frequency module90 with a bidirectional daisy chain coupler interface for coupled powersignals with direct current and radio frequency components according toan embodiment. In the radio frequency system 90, a radio frequencycoupler 42 can be electrically connected to either input/output portCPL1 or CPL2 via a termination and output switch 44 and a coupled poweroutput switch 92. Biasing circuits 93 and 94 can each provide a directcurrent (DC) bias to a respective coupled power signal provided toinput/output port CPL1 or CPL2 when the radio frequency coupler 42 iselectrically connected to an input/output port CPL1 or CPL2.Accordingly, the coupled power signal provided to an input/output portCPL1 or CPL2 can have a DC component and an RF component. The radiofrequency module 90 also includes an RF pass circuit 95 and a DC passcircuit 96 arranged to pass a coupled power signal between input/outputports CPL1 and CPL2. With the RF pass circuit 95 and the DC pass circuit96, the radio frequency module 90 pass a coupled power signal betweeninput/output ports CPL1 and CPL2 when the radio frequency module 90 isotherwise inactive. Accordingly, control of the daisy chain of couplerswitching circuits can be simplified. Power of the radio frequencysystem can also be reduced. The RF pass circuit 95 and the DC passcircuit 96 can both be deactivated when the radio frequency coupler 42is providing a coupled power signal to either of the input/output portsCPL1 and CPL2.

FIG. 10 is a schematic diagram of an example radio frequency passcircuit 100 that can be electrically connected between input/outputports of the radio frequency module 90 of FIG. 9 according to anembodiment. The radio frequency pass circuit 100 can implement the RFpass circuit 95 of FIG. 9.

A DC component of a coupled power signal received at the firstinput/output port CPL1 can be applied to a control terminal of a firstpass transistor 101 via a biasing element 103 to turn on the first passtransistor 101. This can turn on the first pass transistor 101 when aradio frequency module that includes the radio frequency pass circuit100 is otherwise inactive. A DC blocking element 102 can block the DCcomponent of the coupled power signal received at the first input/outputport CPL1 so that the pass transistor 101 passes the RF component of thecoupled power signal to the second input/output port CPL2 when on.

A DC component of a coupled power signal received at the secondinput/output port CPL2 can be applied to a control terminal of a secondpass transistor 105 via a biasing element 107 to turn on the first passtransistor 105. This can turn on the second pass transistor 105 when aradio frequency module that includes the radio frequency pass circuit100 is otherwise inactive. A DC blocking element 106 can block the DCcomponent of the coupled power signal received at the secondinput/output port CPL2 so that the pass transistor 105 passes the RFcomponent of the coupled power signal to the first input/output portCPL1 when on.

When a radio frequency coupler is providing a coupled power signal toeither of the input/output ports CPL1 or CPL2, the active low enablesignal Enable_L can turn off the pass transistors 101 and 105 todeactivate the radio frequency pass circuit 100. This can decouple theinput/output ports CPL1 and CPL2 from each other when one or more radiofrequency couplers are providing a coupled power signal to at least oneof these input/output ports.

FIG. 11 is a schematic diagram of an example direct current pass circuit110 that can be electrically connected between input/output ports of theradio frequency module of FIG. 9 according to an embodiment. The DC passcircuit 110 can implement the DC pass circuit 96 of FIG. 9.

A RF blocking element 112 can block an RF component of a coupled powersignal received at the first input/output port CPL1. As illustrated, theRF blocking element 112 includes a resistor and a capacitor arranged asa low pass filter. The DC component of the coupled power signal receivedat the first input/output port CPL1 can turn on a transistor 113 that inturn turns on a first pass transistor 111. This can turn on the firstpass transistor 111 when a radio frequency module that includes thedirect current pass circuit 110 is otherwise inactive. The first passtransistor 111 can pass the DC component of the coupled power signalreceived at the first input/output port CPL1 to the second input/outputport CPL2 when on.

A RF blocking element 116 can block an RF component of a coupled powersignal received at the second input/output port CPL2. As illustrated,the RF blocking element 116 includes a resistor and a capacitor arrangedas a low pass filter. The DC component of the coupled power signalreceived at the second input/output port CPL2 can turn on a transistor117 that in turn turns on a second pass transistor 115. This can turn onthe second pass transistor 115 when a radio frequency module thatincludes the direct current pass circuit 110 is otherwise inactive. Thesecond pass transistor 115 can pass the DC component of the coupledpower signal from the second input/output port CPL2 to the firstinput/output port CPL1 when on.

When a radio frequency coupler is providing a coupled power signal toeither of the input/output ports CPL1 or CPL2, the active high enablesignal Enable_H can turn off the pass transistors 111 and 115 todeactivate the DC pass circuit 110. This can decouple the input/outputports CPL1 and CPL2 from each other when one or more radio frequencycouplers are providing a coupled power signal to at least one of theseinput/output ports.

FIG. 12 is a schematic diagram of a radio frequency system 120 with abidirectional daisy chain of coupler switching circuits with directcurrent blocking elements 127 and 128 included between the daisy chainand dual feedback receiver inputs according to an embodiment. The radiofrequency system 120 includes radio frequency modules 121, 122, 123,124, 125, and 126 with respective coupler switching circuits arranged ina daisy chain. The coupler switching circuits can pass a coupled powersignal having a DC component and a radio frequency component and toprovide such a coupled power signal to an input/output port. The couplerswitching circuits of the radio frequency modules 121 to 126 can beimplemented in accordance with any suitable principles and advantagesdisclosed with reference to FIGS. 9 to 11. The radio frequency system120 is like the radio frequency system 60 of FIG. 6A, except that (1)the coupler switching circuits of radio frequency modules 121 to 126 areconfigured to pass a coupled power signal with a DC component and an RFcomponent and (2) the direct current blocking elements 127 and 128 canblock the DC component of a coupled power signal from the daisy chainprovided to feedback receiver ports FB Rx1 and RB Rx2, respectively, ofa transceiver. As illustrated, direct current blocking elements 127 and128 can be capacitors. Direct current blocking elements 127 and/or 128can be implemented with a daisy chain of coupler switching circuits inaccordance with any suitable principles and advantages disclosed herein.

FIG. 13 is a schematic diagram of a radio frequency system 130 with abidirectional daisy chain of coupler switching circuits with a directcurrent blocking element 127 between the daisy chain and a singlefeedback receiver input according to an embodiment. The radio frequencysystem 130 is like the radio frequency system 70 of FIG. 7A, except that(1) the coupler switching circuits of radio frequency modules 121 to 126are configured to pass a coupled power signal with a DC component and anRF component and (2) the direct current blocking element 127 can blockthe DC component of coupled power signal from the daisy chain providedto feedback receiver port FB Rx of the transceiver 67.

Radio frequency systems disclosed herein can perform methods of passingradio frequency power through a daisy chain of coupler switchingcircuits. Such methods can be performed in accordance with any suitableprinciples and advantages of the radio frequency modules and/or radiofrequency systems disclosed herein. These methods can involve a coupledpower signal propagating through circuitry of one or more radiofrequency modules that are not actively transmitting while a pluralityof radio frequency modules are actively transmitting. An example methodcan include providing two indications of radio frequency power to adaisy chain of coupler switching circuits while a plurality of radiofrequency modules are concurrently transmitting. A first coupled powersignal generated by a first actively transmitting radio frequency modulecan be provided to the daisy chain. A second coupled power signalgenerated by a second actively transmitting radio frequency module canalso be provided to the daisy chain such that the first and secondcoupled power signals propagate in opposite direction in the daisychain.

The first and second coupled power signals can be received by a feedbackreceiver. The coupled signals can be processed by the feedback receiver.Then one or more adjustments to a transmit path of an activelytransmitting radio frequency module can be performed based on an outputsignal of the feedback receiver.

Wireless Communication Devices

The radio frequency modules and radio frequency systems disclosed hereincan be included in wireless communication devices, such as mobiledevices. An example of such a wireless communication device will bediscussed with reference to FIG. 14.

FIG. 14 is a schematic diagram of one embodiment of a mobile device 800.The mobile device 800 includes a baseband system 801, a transceiver 802,a front end system 803, antennas 804, a power management system 805, amemory 806, a user interface 807, and a battery 808.

The mobile device 800 can be used communicate using a wide variety ofcommunications technologies, including, but not limited to, 2G, 3G, 4G(including LTE, LTE-Advanced, and LTE-Advanced Pro), 5G NR, WLAN (forinstance, WiFi), WPAN (for instance, Bluetooth and ZigBee), WMAN (forinstance, WiMax), and/or GPS technologies.

The transceiver 802 generates RF signals for transmission and processesincoming RF signals received from the antennas 804. It will beunderstood that various functionalities associated with the transmissionand receiving of RF signals can be achieved by one or more componentsthat are collectively represented in FIG. 14 as the transceiver 802. Inone example, separate components (for instance, separate circuits ordies) can be provided for handling certain types of RF signals.

The front end system 803 aids in conditioning signals transmitted toand/or received from the antennas 804. In the illustrated embodiment,the front end system 803 includes antenna tuning circuitry 810, poweramplifiers (PAs) 811, low noise amplifiers (LNAs) 812, filters 813,switches 814, and signal splitting/combining circuitry 815. However,other implementations are possible. The filters 813 can include one ormore tunable filters with harmonic rejection with that include one ormore features of the embodiments disclosed herein.

For example, the front end system 803 can provide a number offunctionalities, including, but not limited to, amplifying signals fortransmission, amplifying received signals, filtering signals, switchingbetween different bands, switching between different power modes,switching between transmission and receiving modes, duplexing ofsignals, multiplexing of signals (for instance, diplexing ortriplexing), or some combination thereof.

In certain implementations, the mobile device 800 supports carrieraggregation, thereby providing flexibility to increase peak data rates.Carrier aggregation can be used for both Frequency Division Duplexing(FDD) and Time Division Duplexing (TDD), and may be used to aggregate aplurality of carriers or channels. Carrier aggregation includescontiguous aggregation, in which contiguous carriers within the sameoperating frequency band are aggregated. Carrier aggregation can also benon-contiguous, and can include carriers separated in frequency within acommon band or in different bands.

The antennas 804 can include antennas used for a wide variety of typesof communications. For example, the antennas 804 can include antennasfor transmitting and/or receiving signals associated with a wide varietyof frequencies and communications standards.

In certain implementations, the antennas 804 support MIMO communicationsand/or switched diversity communications. For example, MIMOcommunications use multiple antennas for communicating multiple datastreams over a single radio frequency channel. MIMO communicationsbenefit from higher signal to noise ratio, improved coding, and/orreduced signal interference due to spatial multiplexing differences ofthe radio environment. Switched diversity refers to communications inwhich a particular antenna is selected for operation at a particulartime. For example, a switch can be used to select a particular antennafrom a group of antennas based on a variety of factors, such as anobserved bit error rate and/or a signal strength indicator.

The mobile device 800 can operate with beamforming in certainimplementations. For example, the front end system 803 can includeamplifiers having controllable gain and phase shifters havingcontrollable phase to provide beam formation and directivity fortransmission and/or reception of signals using the antennas 804. Forexample, in the context of signal transmission, the amplitude and phasesof the transmit signals provided to the antennas 804 are controlled suchthat radiated signals from the antennas 804 combine using constructiveand destructive interference to generate an aggregate transmit signalexhibiting beam-like qualities with more signal strength propagating ina given direction. In the context of signal reception, the amplitude andphases are controlled such that more signal energy is received when thesignal is arriving to the antennas 804 from a particular direction. Incertain implementations, the antennas 804 include one or more arrays ofantenna elements to enhance beamforming.

The baseband system 801 is coupled to the user interface 807 tofacilitate processing of various user input and output (I/O), such asvoice and data. The baseband system 801 provides the transceiver 802with digital representations of transmit signals, which the transceiver802 processes to generate RF signals for transmission. The basebandsystem 801 also processes digital representations of received signalsprovided by the transceiver 802. As shown in FIG. 14, the basebandsystem 801 is coupled to the memory 806 of facilitate operation of themobile device 800.

The memory 806 can be used for a wide variety of purposes, such asstoring data and/or instructions to facilitate the operation of themobile device 800 and/or to provide storage of user information.

The power management system 805 provides a number of power managementfunctions of the mobile device 800. In certain implementations, thepower management system 805 includes a PA supply control circuit thatcontrols the supply voltages of the power amplifiers 811. For example,the power management system 805 can be configured to change the supplyvoltage(s) provided to one or more of the power amplifiers 811 toimprove efficiency, such as power added efficiency (PAE).

As shown in FIG. 14, the power management system 805 receives a batteryvoltage from the battery 808. The battery 808 can be any suitablebattery for use in the mobile device 800, including, for example, alithium-ion battery.

Applications, Terminology, and Conclusion

Any of the embodiments described above can be implemented in associationwith mobile devices such as cellular handsets. The principles andadvantages of the embodiments can be used for any systems or apparatus,such as any uplink wireless communication device, that could benefitfrom any of the embodiments described herein. The teachings herein areapplicable to a variety of systems. Although this disclosure includesexample embodiments, the teachings described herein can be applied to avariety of modules, systems, devices, and methods. Any of the principlesand advantages discussed herein can be implemented in association withRF circuits configured to process signals having a frequency in a rangefrom about 30 kHz to 300 GHz, such as in a frequency range from about450 MHz to 8.5 GHz.

Aspects of this disclosure can be implemented in various electronicdevices. Examples of the electronic devices can include, but are notlimited to, consumer electronic products, parts of the consumerelectronic products such as packaged radio frequency modules, radiofrequency filter die, uplink wireless communication devices, wirelesscommunication infrastructure, electronic test equipment, etc. Examplesof the electronic devices can include, but are not limited to, a mobilephone such as a smart phone, a wearable computing device such as a smartwatch or an ear piece, a telephone, a television, a computer monitor, acomputer, a modem, a hand-held computer, a laptop computer, a tabletcomputer, a microwave, a refrigerator, a vehicular electronics systemsuch as an automotive electronics system, a robot such as an industrialrobot, an Internet of things device, a stereo system, a digital musicplayer, a radio, a camera such as a digital camera, a portable memorychip, a home appliance such as a washer or a dryer, a peripheral device,a wrist watch, a clock, etc. Further, the electronic devices can includeunfinished products.

Unless the context indicates otherwise, throughout the description andthe claims, the words “comprise,” “comprising,” “include,” “including”and the like are to generally be construed in an inclusive sense, asopposed to an exclusive or exhaustive sense; that is to say, in thesense of “including, but not limited to.” Conditional language usedherein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,”“for example,” “such as” and the like, unless specifically statedotherwise, or otherwise understood within the context as used, isgenerally intended to convey that certain embodiments include, whileother embodiments do not include, certain features, elements and/orstates. The word “coupled”, as generally used herein, refers to two ormore elements that may be either directly connected, or connected by wayof one or more intermediate elements. Likewise, the word “connected”, asgenerally used herein, refers to two or more elements that may be eitherdirectly connected, or connected by way of one or more intermediateelements. Additionally, the words “herein,” “above,” “below,” and wordsof similar import, when used in this application, shall refer to thisapplication as a whole and not to any particular portions of thisapplication. Where the context permits, words in the above DetailedDescription using the singular or plural number may also include theplural or singular number respectively.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosure. Indeed, the novel filters, wirelesscommunication devices, apparatus, methods, and systems described hereinmay be embodied in a variety of other forms. Furthermore, variousomissions, substitutions and changes in the form of the filters,wireless communication devices, apparatus, methods, and systemsdescribed herein may be made without departing from the spirit of thedisclosure. For example, while blocks are presented in a givenarrangement, alternative embodiments may perform similar functionalitieswith different components and/or circuit topologies, and some blocks maybe deleted, moved, added, subdivided, combined, and/or modified. Each ofthese blocks may be implemented in a variety of different ways. Anysuitable combination of the elements and/or acts of the variousembodiments described above can be combined to provide furtherembodiments. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the disclosure.

What is claimed is:
 1. A radio frequency module comprising: a firstinput/output port; a second input/output port; a radio frequencycoupler; and a coupler switching circuit configured to pass anindication of radio frequency power received at the first input/outputport to the second input/output port, pass an indication of radiofrequency power received at the second input/output port to the firstinput/output port, and provide an indication of radio frequency powerfrom the radio coupler to the first input/output port.
 2. The radiofrequency module of claim 1 wherein the coupler switching circuit isconfigured to provide the indication of radio frequency power from theradio frequency coupler to the second input/output port.
 3. The radiofrequency module of claim 1 wherein the indication of radio frequencypower is an indication of forward radio frequency power, and the couplerswitching circuit is configured to provide an indication of reflectedradio frequency power from the radio frequency coupler to the firstinput/output port.
 4. The radio frequency module of claim 3 wherein thecoupler switching circuit is configured to provide the indication ofradio frequency power to the second input/output port and to provide theindication of reflected radio frequency power to the second input/outputport.
 5. The radio frequency module of claim 1 further comprising apower amplifier having an output electrically coupled to the radiofrequency coupler.
 6. The radio frequency module of claim 5 furthercomprising one or more circuit elements in a signal path between theoutput of the power amplifier and the radio frequency coupler.
 7. Theradio frequency module of claim 6 wherein the one or more circuitelements include a switch.
 8. The radio frequency module of claim 1further comprising a second radio frequency coupler, the couplerswitching circuit configured to provide an indication of radio frequencypower from second radio frequency coupler to the first input/outputport.
 9. The radio frequency module of claim 1 wherein the couplerswitching circuit includes a plurality of switches arranged to pass theindication of radio frequency power received at the first input/outputport to the second input/output port, pass the indication of radiofrequency power received at the second input/output port to the firstinput/output port, and provide the indication of radio frequency powerfrom the radio coupler to the first input/output port.
 10. The radiofrequency module of claim 10 wherein the plurality of switches includesa switch configured to selectively electrically connect a terminationimpedance to a port of the radio frequency coupler.
 11. A radiofrequency system comprising: a first radio frequency module including afirst port and a first coupler switching circuit; a second radiofrequency module including a second coupler switching circuit; and athird radio frequency module including a first input/output port, asecond input/output port, a radio frequency coupler, and a third couplerswitching circuit, the third coupler switching circuit being included ina daisy chain that also includes the first and second coupler switchingcircuits, the third coupler switching circuit configured to pass anindication of radio frequency power received at the first input/outputport to the second input/output port, pass an indication of radiofrequency power received at the second input/output port to the firstinput/output port, and provide an indication of radio frequency powerfrom the radio coupler to the first input/output port.
 12. The radiofrequency system of claim 11 wherein the third coupler switching circuitis configured to provide the indication of radio frequency power fromthe radio frequency coupler to the second input/output port.
 13. Theradio frequency system of claim 11 wherein the indication of radiofrequency power is an indication of forward radio frequency power, andthe third coupler switching circuit is configured to provide anindication of reflected radio frequency power from the radio frequencycoupler to the first input/output port.
 14. The radio frequency systemof claim 11 wherein the third radio frequency module further includes asecond radio frequency coupler, and the third coupler switching circuitis configured to provide an indication of radio frequency power fromsecond radio frequency coupler to the first input/output port.
 15. Theradio frequency system of claim 11 wherein the first radio frequencymodule and the second radio frequency module are configured to transmitconcurrently.
 16. The radio frequency system of claim 15 wherein theradio frequency system is configured to concurrently pass a firstindication of radio frequency power from the first radio frequencymodule and a second indication of radio frequency power from the secondradio frequency module in different directions in the daisy chain. 17.The radio frequency system of claim 11 further comprising a feedbackreceiver having an input port electrically coupled to the daisy chain.18. A wireless communication device comprising: a radio frequency moduleincluding a first input/output port; a second input/output port; a radiofrequency coupler; and a coupler switching circuit configured to pass anindication of radio frequency power received at the first input/outputport to the second input/output port, pass an indication of radiofrequency power received at the second input/output port to the firstinput/output port, and provide an indication of radio frequency powerfrom the radio coupler to the first input/output port; and an antenna incommunication with the radio frequency module and configured to transmita radio frequency signal generated by the radio frequency module. 19.The wireless communication device of claim 18 further comprising twoadditional radio frequency modules each including a respective couplercircuit that is included in a daisy chain with the coupler circuit ofthe radio frequency module.
 20. The wireless communication device ofclaim 19 wherein the wireless communication device is configured toconcurrently pass two indications of radio frequency power in opposingdirections in the daisy chain.